Electric fuse



Nov- 13 1923 RQFOLDS ELECTRIC FUSE Filed Nov. 20. 1920 outer air through restricted passageways idl' f an Patented Nov. 13, 1923.

UNITED STATES PATENT OFFICE.

GEORGE FOLDS, OFCHICAGO, ILLINOIS, ASSIGNOE. TO COOK ELECTRIC COMPANY, i

OF CHICAGO, ILLINOIS, A CORPORATION 0F ILLINOIS.

ELECTRIC FUSE.

Application aieanavemberao, 1920. semi no. 425,509.-

To all whom t may concern:

Be it known that I, Gnome l. Fonos, a citizen of the United States, residing at C'hicago, in the county of Cook and State of Illinois, have invented new and useful Improvenients in Electric Fuses, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawing, forming a part of this specification.

My invention ielates'to enclosed renewable electric fuses and more particularly to improved electric fuses of the foregoing character in which the chamber containing the fusible element communicates with the which extend through the end portions o'. the enclosed fuse. Moreover, by my present invention, I am able to limit the length of the fusible element that isconsumed 0r vaporized at the time of the exploding of the fuse, without employing 4a specially'designed fusible element for this purpose.

The venting in my present enclosed fuse is effected at each end through a tortuous and restricted passageway that is formed in a washer and continues through a portion of the fusible element and a terminal member which, in the present instance, and for the purpose of illustration only, is shown as a knife-blade terminal.

The washer comprising the restricted and tortuous venting passageway isof substantial mass and is disposed closely adjacent to the fusible element or link so that when this link is va-porized the mass of the said washer vwill serve to quickly cool the resulting vapors and flames. n addition to the cooling effect occasioned by the mass of the washer, the restricted and tortuous passageway for venting the vapors from the fuse precludes any fire or flame from extending exteriorly of the fuse. It is obviousy that the venting of the fuse may be effected through means other than the agency of the washer but that if the washeris of substantial mass, it will serve to rapidly cool the gases and vapors at the time ofthe blowing of 'the fuse. 1

An object, therefore, of my invention is to provide a fire-proof enclosed renewable fuse which comprises elements that may be 4recurrently used, with the exception of the fusible link, and .which kprecludes any fire (fir flame from -extending exteriorly of the use.k 4 Y i .Another'object of my invention is to providean economical fuse of the above indi- ,cated character which may be readilymanand, positioned in proximity to the fusible element in order that theymay serve to rapand effectively' cool the burning gases vapors arising from the-consumption of the fusible' element. In this fashion, the consumed portion of the fusible element is restricted practicallyto-the portion thereof that extends between the two opposed and spaced end faces of the two washers. By this arrangement of parts and because of the nature of the washers I propose using, the fusible element will be only partially con sumed. l

Fora lbetter understanding of the nature and the scope' of my invention reference may be had to the following description and the accompanying drawing; in which- Fig. 1 is a side view, partially in section, of an enclosed renewable fuse embodying a form of my invention;

Fig. 2 is a cross sectional view taken along the line 2-2 of Fig. l;

Fig. 3 is across sectional the line 3 3 of Fig. l;

Fig. 4 is a cross sectional view taken along vthe line 4--4 of Fig. 1.;

Fig. 5 is a partially exploded view showifng some vof the elements comprised `in my use;

Fig. 6 isa view showing in perspective the two members that comprise the removable washer comprised in my fuse;

Fig. 7 is a cross sectional view showin a modified form of renewable washer, an

Fi 8 is a cross 'sectional view taken along the line 8-.8 of Fig. 7.

Referring to the drawing, an insulating and enclosin shell l, in which a fusible link 2 is posltioned, is provided at each of its ends with a metal ferrule 3. Each metal ferrule 3 is interiorly threaded t0 engage the end portions of the insulating shellvl. The outer end of each ferrule 3 is provided with an annular Aortion 4 that serves as a seat for a metallic washer 5. The outer surface of the annular portion 4 of each ferrule 3 is exteriorly threaded to engage a cap member 6 that comprises a portion of the terminal structure 7.

It will be observed by referring to Fig. 6 that the washer (designated as 5 in Figure 1) comprises a main member 8 and a plug member 9. The main member 8 is shown as being of friisto-conical form and so positioned in the assembled fuse that its apex is directed inwardly. The base of the mem,- ber 8 is provided with a beveled flange 9 that is recessed at 10. The flange 9a in the removable washer 5 (Fig. 1) is positioned upon a seat provided by the annular portion 4 of the ferrule -3 and thus a tight joint therebetween is procured so as to substantially eliminate the venting of the fuse between the ferrule 3 and the washer 5.

The member 8 is provided with a central bore 11 which, in the drawing, is shown as a smooth bore. The plug 9, which is exteriorly threaded throughout its entire length and shown for the purpose of illustration only as being provided with a square thread, is fitted in the bore 11 with a drive fit. The inner end of the bore 11 is countersunk as shownat 12 and this countersunk portion 12 opens through the base of the main member 8 through an opening 13. The thread formed upon the plug 9 constitutes a restricted tortuous passageway having the form of a. helix that extends through the assembled Washer 5. The length or area of the venting path may be controlled by changing the size and pitch of screw thread.

Referring to Fig. 5 it will be observed that the fusible link 2 has each of its end portions rounded as at 14 these portions 14 being curved oppositely with respect to each other. The extreme ends of the portions 14 are bent over to form flat terminals 15 in which holes 16 are punched. The rounded por-` tions 14 of the link 2 are received in the recesses 10 formed in the washer member 8.

By reason of the Washer member 8 being joint between the annular portion 4 of the ferrule 3 and the washer 5 continuous. The hole 16 formed in the terminal portion 15 of the link 2 registers with the opening 13 formed in the washer 5.

In Fig. 1 the terminal structure 7 comprises the cap 6 that is referably pressed from a steel punching. l`he lower edge of the cap is internally threaded at 19 to engage the exterior thread formed on the annular portion 4 of the fel-rule 3. A knifeblade terminal 20 is provided with two integral projecting lugs 2l and extends through a central opening ot the cap 6. The lugs 21 project through a base plate 22 and a retaining member 22, the former being preferably made of copper. The lugs 21 are peened so as to firmly rivet the blade terminal 2O to the base plate 22 and the member 22a.

A V-shaped notch 23 is cut in the central portion, and at the base, of the knife-blade terminal 20 and registers with an opening 24 that is formed in the base plate 22 and the member 22a. The opening 13 formed at the base of the washer 5 thus communirates with the outer air through the opening 16 in the link 2. the opening 24 in the base plate 22 and the retaining member 22a and the V-shaped notch 23 in the knife-blade 20.

The passageway from the interior of the insulating shell to the outer air is very advantageously terminated Iby the notch 23. Since the knife-blade terminal member 2() serves to guard this opening thus provided by the notch 23 it is thereby prevented from being clogged by dirt or other foreign matter. The notch 23 furthermore permits the locating of the opening 13 in the washer in a convenient central position even when the terminal ,members comprising knife-blade portions are used. It will be noted that because of the thickness ot the flanges on the cap member 6, as shown in Fig. 1, the notch 23 is precluded from being covered up by any clips or spring members that may be employed to engage with the knife-blade terminals 20 ofthe fuse.

In order that. the knife-blade members 20 may be in proper alignment, a notch 25 is cut in the annular portion 4 of the ferrule 3 as shown in F ig. 5. A properly positioned lug 26 is upset on the periphery of the rim of the base-plate 22 of the terminal Structure 7, which lng is adapted to engage the notch 25 when the terminal structure 7 occupies its proper relative position. The cap member 6 which slidingly engages the base plate 22 is then screwed down to retain the knife blade 2O in a fixed position.

lVhile I have shown the terminal member 7 as comprising a knife blade 20, it will be apparent that my present fuse is not limited to a knife-blade construction only, inasmuch as other types of fuses may embody my invention, as will be apparent to those skilled in the art.

Referringlto Figs. 7 and 8, I have shown lill) the internal bore 11 of the main member 8 of the washer 5 as being provided with a square bottom, The plug 9 has its inner end transversely slotted at Q7, `which slot is cut sufiiciently deep to reach the base of the screw thread formed on the plug 9. The slot 27 is sovlocated that it bridges the opening 13. The tortuous helical passageway formed by the screw thread cut 1n the plug 9 thus communicates with the outer air through the slot Q7 and the opening 13.

From the foregoing description, it will be observed that the washer member 5 is of substantial mass and in closemechanical contact with the fusible` link 2 throughout a substantialportion ot' the length of the fuse. The washer 5 being made entirely of metal has high heat conductive .and absorptive qualities and thereby tends to readily cool any hot gases or flames comin in ycontact therewith. Again, the ends o the fusible link, by reason of their being in close proxiinity to the washers 5, are not likely to vaporize when the fuse is blown because the mass of the washers 5 quickly absorbs the heat affecting the fusible link, and, therefore, protects the ends of said link from va orizing. At the same time, the restricted an tortuous passageway formed throughout the length of the washer 5 serves to adequately ventilata the fuse and ensure further cooling of the heated vapors and flames. On the blowing of the fuse, the -rush of gases and vapors through the tortuous `passageway produces a suction action drawing the flames and fire likewise through the passageways. This tends to cool-the flames and extinguish them before passing exteriorly of the fuse. However, other means may be provided for the venting of the fuse, the washers in this-instance serving only to cool the vapors and thereby limit-ing the portion of the fusible link that is consumed.

I am able to accomplish these desirable results by means of the washer 5. This is economically constructed by m use of the screw thread formed on the p ug 9, which thus provides a helical passageway of considerable length. It will be obvious that the screw thread serving as the venting passageway need not be confined to the plug 9 but one or the other of the opposing faces should, in any ev:nt, be threaded to form a tortuous venting path. For the purpose of economical construct-ion, it is however, preferable to construct the washer as illustrated. Although the main member 8 is shown as being of frusto-conical shape, it will beunderstood that I do not propose to limit the washer to such a construction.

While I have shown and described in detail an embodiment of my invention it is to be understood that I deslre only such lmitations to be placed thereupon as are required by the state of the prior art and specifically set forth in the appended claims.

Having thus described my invention owhat lwasher and adjacent to said threaded plug.

2. In an enclosed renewable electric fuse, a removable washer having a tortuous venting path therein which is adjacent to a screw thread formed on one of the elements comprising-said washer.

3. Inl an enclosed renewable electric fuse, a removable washer comprising a main member, and an auxiliary member, one of the adjacent surfaces between said members having. formed thereupon a helical venting path that restricts the venting of the fuse. p

i 4. In an enclosed renewable electric fuse, a removable washer'of frusto-conical shape having a helical, screw-thread path formed therein which serves to'vent the interior-of the fuseto the outer air.

5. In an enclosed renewable electric fuse,a removable washer having a tortuous -restricted path formed therein for venting the fuse, said washer being of substantial mass and high heat conductivity adjacent to said tortuous path to ensure the cooling of the vapors and the flames tending to travel along said tortuous path.

`6. In an enclosed renewable electric fuse, a removable washer comprising a main member having a central bore, and a plug adapted to fit in 'said bore, the adjacent surfaces of contact between said main member and said plug providing a helical path in the form of a screw thread for restrictively Venting the fuse.

7. In an enclosed renewable electric fuse, a removable washer comprising a main member having a smooth longitudinal bore formed therein, and an exteriorly threaded plug inserted in said bore by a drive fit to provide a tortuous path through said washer. h

8. In an enclosed renewable electric fuse, the combination of a `fusible link extending longitudinally of the fuse and having bentover ends, with washers for severally `engaging said link `at its ends, each of said washers having'an inwardly projecting extension that conforms to the contour of the. associated link-end and being provided with a tortuous venting path thatl extends in said projecting extension for cooling and restricting the flow of gases and flames exteriorly of the fuse.

9. In an enclosed renewable electric fuse comprising a shell member, a fusible link, and members within said shell member for severally engaging ends of said link, said end members being severally provided with a restricted tortuous path tor venting the fuse and being of substantial mass and high heat conductivity so that the end members serve to sutiiciently cool the vapors prior to their exhaust through said venting passageways.

10. In an enclosed renewable electric fuse comprising a shell member, a fusible link, and end members contained within said shell member and in contact with said fusible link. said end members being of subst-antial mass and of high heat conductivity, a tortuous passageway being formed in said end members for restrictively venting the fuse therethrough,

11. In` an enclosed renewable electric fuse comprising an insulatingr shell member. a fusible link, and end members housed within said insulating shell member and being of .substantial mass and of high heat conductivity, a tortuous passageway being formed in each of said end members for restrictively venting the insulating shell member therethrough.

12. An enclosed electric fuse comprising a shell member` and a terminal member engaging the end of said shell member` said terminal member comprising a knife-blade portion joined to a base plate at substan tially right angles thereto, said base plate being provided with a vent-hole at its junction with said knife-blade portion and said knife-blade portion being provided with a notch adjacent said vent hole.

13. An electric fuse comprising a shell member, a base plate engaging the end of said shell member, and a knife-blade terminal joined to the outside ot said base plate at substantially right angles thereto and centrally thereof, said plate having a central vent-hole and said knife-blade terminal being provided with a notch adjacent to said vent hole.

In witness whereof` I have hereunto subscribed my name.

GEORGE R. FOLDS.

Witnesses H. W. Doven, ALBERT M. Wxnxms. 

